/**
 *       Copyright (c) 2012 Lukas Zaruba
 *
 *   This file is part of Robot Playground.
 *
 *   Robot Playground is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Robot Playground is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with Robot Playground. If not, see <http://www.gnu.org/licenses/>.
 */
package net.zarubsys.commons.scripting.functions.strings;

import java.util.List;

import net.zarubsys.commons.scripting.IScriptFunction;
import net.zarubsys.commons.scripting.ParsedStatement;
import net.zarubsys.commons.scripting.ScriptingEnvironment;
import net.zarubsys.commons.scripting.ScriptingException;
import net.zarubsys.commons.utils.StringUtils;

/**
 * Based on scripting language from Media Solutions Slovakia, a.s.
 * @author Lukas Zaruba, lukas.zaruba@gmail.com
 */
public class SubstringFunction implements IScriptFunction {

	@Override
	public Object execute(ScriptingEnvironment env, List<ParsedStatement> args) throws ScriptingException {
		String source = StringUtils.toString(args.get(0).execute(env));
		if (source == null) {
			throw new ScriptingException("Source cannot be null!", env.getCurrentScriptLocator());
		}
		int begin = 0;
		int end;
		if (args.size() == 3) {
			begin = Integer.parseInt(StringUtils.toString(args.get(1).execute(env)));
			end = Integer.parseInt(StringUtils.toString(args.get(2).execute(env)));
		} else {
			end = Integer.parseInt(StringUtils.toString(args.get(1).execute(env)));
		}
		
		if (end > source.length()) {
			end = source.length(); 
		}
		if (begin > end || begin > source.length() - 1) {
			throw new ScriptingException("Begin index is bigger than end index or length of the source string. (begin=" + 
					begin + ", end=" + end + ", length="+ source.length() + ")", env.getCurrentScriptLocator());
		}
		
		return source.substring(begin, end);
	}

	@Override
	public int getMaxArgsNum() {
		return 3;
	}

	@Override
	public int getMinArgsNum() {
		return 2;
	}

	@Override
	public String getName() {
		return "substring";
	}

}
